The role of reciprocal activation of cAbl and Mst1 in the Oxidative death of cultured astrocytes

• Published in: Glia 2014-04, Vol.62 (4), p.639-648
• Main Authors: Lee, Sook-Jeong, Seo, Bo-Ra, Choi, Eui-Ju, Koh, Jae-Young
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Astrocytes - drug effects; Astrocytes - physiology; astrocytic death; Benzamides - pharmacology; cAbl; Cell Death - drug effects; Cells, Cultured; Cerebral Cortex - cytology; Chelating Agents - pharmacology; Ethylenediamines - pharmacology; Hepatocyte Growth Factor - genetics; Hepatocyte Growth Factor - metabolism; Hydrogen Peroxide - toxicity; Imatinib Mesylate; Matrix Metalloproteinase 16 - deficiency; metallothioneins; Mice; Mice, Transgenic; oxidative injury; Oxidative Stress - drug effects; Oxidative Stress - physiology; Piperazines - pharmacology; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-abl - genetics; Proto-Oncogene Proteins c-abl - metabolism; Pyrimidines - pharmacology; RNA Interference; RNA, Small Interfering - genetics; RNA, Small Interfering - pharmacology; Zinc - pharmacology
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.22631

The protein kinase Mst1 (mammalian Sterile 20‐like kinase 1) likely plays a role in oxidative neuronal cell death as a target of its activator, cAbl. We previously found that H2O2‐induced death of astrocytes is mediated by cAbl in a metallothionein‐3 (Mt3)‐dependent manner. In the present study, we examined a possible role for Mst1 in the oxidative death of astrocytes. Treatment of cortical astrocytes with 170 µM H2O2 activated Mst1. Knockdown of Mst1 reduced H2O2‐induced cell death, indicating that Mst1 activation contributes to astrocytic cell death. STI571, an inhibitor of cAbl, blocked induction/activation of Mst1 and H2O2‐induced cell death. However, Mst1 silencing also inhibited induction/activation of cAbl, suggesting that the two kinases are regulated by a reciprocal activating mechanism. The zinc chelator TPEN blocked induction/activation of cAbl and Mst1, indicating that these phenomena are dependent on the rise of intracellular zinc. Moreover, H2O2 exposure did not increase free zinc levels in Mt3‐null astrocytes, suggesting that the increased levels of free zinc were largely from Mt3. Consistent with the involvement of FoxO1/3, which may play a role in the Mst1‐cell death cascade, we found an increase in the level of phosphorylated FoxO1/3 in H2O2‐treated astrocytes. Moreover, inhibition of cAbl or Mst1 reversed this effect. The present results suggest the interesting possibility that cAbl and Mst1 are reciprocally activated under oxidative stress conditions in astrocytes. Both kinases appear to be regulated by changes in the levels of free zinc originating from Mt3 and contribute to oxidative cell death through a FoxO‐dependent mechanism. GLIA 2014;62:639–648 Main Points cAbl and Mst1 kinases are induced and activated in a reciprocal manner in cultured astrocytes under oxidative stress. These kinases are regulated by free zinc released from Mt3, and contribute to cell death in a FoxO‐dependent mechanism.